Why does Walton lose his sympathy for the creature Frankenstein chapters 22-24

In "Frankenstein" by Mary Shelley, Walton loses his sympathy for the creature because Victor tells him that the creature murdered his brother, best friend, and bride. Walton agrees to continue the mission to carry out Victor's vengeance after his death. What Walton is not aware of, is that Victor had an agreement with his creation, and did not hold true to his word, causing the creature to destroy everything that was important to Victor.